The Plastic Injection Moulding Process: Explained

what is the plastic injection moulding process

February 08, 2021

Joanne Armstrong

Plastic Injection Moulding

The plastic injection moulding process is straightforward and simple – this is one of the many draws to businesses using this technique. Plastic injection moulding is one of the most popular techniques used for mass-produced products – but why? And how does it work? 

Firstly, plastic injection moulding is regarded as one of the most cost-effective and quick plastic manufacturing techniques. In a world of impatient buyers, speed is everything! But not only does the process have to be quick, it has to be fast and able to deliver too. If there’s a compromise on quality for speed, it won’t bode well with the end result. 

In this post, we cover everything you need to know about the plastic injection moulding process. We’ll walk you through the process from start to finish, therefore, you can expand your knowledge around plastic injection moulding and be more realistic with your expectations in the production stage. 


We’ll cover: 


What is Plastic Injection Moulding? A Recap

Plastic injection moulding is one of the most common plastic manufacturing techniques used around the world. It can lend itself to a wide range of products and industries, which makes it attractive to a wide audience. Having that mass appeal can be beneficial and allow businesses to take advantage of a large potential customer pool. 

The plastic injection moulding process starts with the melting of plastic pellets. Once they’ve reached the correct temperature, materials will be injected into moulds that meet the bespoke requirements of the custom job. Once they’re cooled, set and formed by this mould, you’ll have your end product straight away.

That’s a whistle-stop overview – but don’t worry, we’ll dig a little deeper in the following sections. It’s increasingly popular for businesses due to the high quality standards that can be achieved in a short time. If you can have orders turned around quickly, that’s far more beneficial for your business and allows you to implement your products as soon as possible. 

It’s cost-effective, which is a huge draw for businesses. Of course, if you can minimise costs while still achieving high standards, that’s perfect. Quite simply, you won’t find many businesses complaining about that. Whereas, if products are expensive and of poor quality, you may be on the receiving end of disgruntled customers.


The Plastic Injection Moulding Process – Outlined

Having mentioned the plastic injection moulding process very briefly, this section will cover it a lot more in-depth. Firstly, materials will be prepared and then placed into the heated barrel within the machine. At this stage, the plastic is heated up and melted down – keeping materials at a homogeneous consistency throughout the process

Consistency is everything. If it’s not heated up enough, you’ll find that the product isn’t as flexible or malleable – that way, you’ll be looking at far inferior products. Once they’ve reached the correct consistency, they’ll be pressured into temperature-controlled heat moulds. This is where your end product will start to take shape. 


injection moulding process


These moulds are often bespoke and custom made. Once they’ve been filled, the temperature-controlled moulds will start to cool down the materials. After reaching an adequate temperature, the product will be ejected and you’ll be left with a finished product. Of course, the cooling temperature is crucial – release too early and you’ll be left with an unfinished product. 

And that’s it – the plastic injection moulding process is really that simple. It’s quick and super effective – and thousands of units can be churned out per hour. So, if you’re looking for large orders, you needn’t worry about the time taken to turn them around at all. 


The Importance of the Right Equipment for the Process

Plastic injection moulding is carried out in an innovative and technical machine. As with a lot of industrial processes, if you don’t have the right machine, the quality of your work will be mediocre. As a business, you want to be able to trust that the plastics manufacturer you’re opting for has the right equipment and set up to carry out a good job, don’t you? 

As we briefly mentioned, during the injection moulding process, the consistency of materials is everything. So, if manufacturers have machines that can’t get the consistency right at the melting stage, they’re going to struggle to produce high-quality products. The right consistency ensures that the right amount of materials can be pressed into each mould. 

Of course, the temperature is important too. Firstly, the machine needs to be able to heat the plastic to a point where adequate consistency can be achieved. Once the materials are in the moulds, the machine should aid the moulds in cooling down the materials before releasing the end product. 

Should the temperature element be broken on a machine, you could be in for a world of bother at the different stages of the injection moulding process. This is why you need to find an injection moulding specialist that you can trust and rely on to get the job done. Always do your research before entering any long-term partnership.

Key Project Benefits of Plastic Injection Moulding


When organising a project, managing a budget is a huge part of the project being a success – especially when manufacturing products is concerned. You’ll likely be judged on the price-per-unit, so you need to make sure your manufacturing choice is as cost-effective as possible. 

With plastic injection moulding, you can be sure that cost-effectiveness is always of the highest regard. Plus, key project stakeholders will also be impressed by the quality and longevity of the products you’ve had manufactured in relation to the price paid. 



As a manufacturing technique, plastic injection moulding can lend itself to a wide variety of industries. For businesses and projects, that’s good. For example, if you need two different products creating within the same project, that’s easily done with one plastic manufacturer – no unnecessary fussing around. 


Andrew Plastics plastic injection moulding flexibility


Plus, bespoke is standard with plastic injection moulding! Your individual needs and requirements will always be taken into account. You can be assured that your unique specifications will be met. 


Quick Turnaround Times

Due to the simplicity of the injection moulding process, your order will be turned around quickly from your chosen manufacturer. This is a bonus for your business as you may need the product urgently to help improve your overall operations. Or, it could be the latest product to fly off your shelves – either way, orders will be fulfilled in a very timely manner. 

Not only will they be actioned quickly, but they’ll also be very high-quality products. There’s nothing worse than manufacturers compromising quality for speed – FACT.


Find Out More About Plastic Injection Moulding

Now that you’ve got the plastic injection moulding process locked down, why not expand your knowledge about the potential products and industries that can be supported by it? At Andrew Plastics, we’re here to educate the industry so you can make wiser decisions when it comes down to plastic manufacturing. 

Our expert team is always on hand to answer any questions or queries that you may have – please don’t hesitate to get in touch with us. Or, if you’d like some further reading, we’ve put together a full guide that highlights everything you need to know about plastic manufacturing. And best of all, our comprehensive guide is free to download! 

From the different manufacturing techniques, who we are, typical industries and much more – it’s all in there for you to digest. Waste no time and grab your copy today!

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